NestMathFree financial tools for the decisions that matter.
Free calculators for every home buying decision. No account. Your data stays on your device.
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Home price, rate, rent. Takes about 30 seconds.
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BUDGET MODULE
Where is my money going?
Enter your pre-tax income and monthly expenses to see your real take-home, track where it goes, and project your savings over time.
CalculateHOME MODULES
Should I buy or rent?
Model the full financial picture of buying vs. renting: equity, opportunity cost, and the exact year buying pays off.
CalculateHow much house can I afford?
Work backward from your income to find your real buying power.
CalculateWhat if I pay extra each month?
See how extra payments shrink your loan term and total interest paid.
CalculateINVEST MODULES
How much will my savings earn?
Compare HYSA growth against a traditional savings account over time.
CalculateHow much do fees cost me?
See the compounding dollar drag of a high-fee fund vs. a low-cost alternative.
CalculateAm I on track to retire?
Project your 401(k) balance at retirement and see the real value of your employer match.
CalculateWhich IRA saves me more in taxes?
Compare Roth vs. Traditional IRA after-tax wealth based on your current and future tax rates.
CalculateWhen should I claim Social Security?
Find the optimal claiming age and your personal break-even point between early and late benefits.
CalculateLIFE MODULES
Should I stay or switch jobs?
Model cumulative earnings for a raise vs. a new offer and find the break-even year.
CalculateIs renovating worth it?
Compare renovation returns against putting that same cash in the market.
CalculateShould I lease or buy a car?
True three-way comparison: lease, buy, or buy cheaper and invest the difference.
CalculateWhat am I actually making?
Adjust for commute, unpaid overtime, and expenses to find your true hourly rate.
CalculateAm I withholding enough from my paycheck?
See your estimated tax bill vs. current withholding and whether you owe at filing time.
CalculateWhat does freelance income net after taxes?
Calculate self-employment tax, deductions, and your real take-home from side work.
CalculateDEBT MODULES
When will my credit card be paid off?
See your payoff date and how much interest you save vs. paying only the minimum.
CalculateWhen will my student loans be gone?
See your payoff date and how much extra payments save over the life of your loans.
CalculateAvalanche or snowball: which saves more?
Compare debt payoff strategies across multiple debts and see which keeps more in your pocket.
CalculateFAQ
Is it better to buy or rent right now?
Your timeline and local market determine the answer. The buy vs. rent calculator shows the exact year when buying pulls ahead, based on your home price, mortgage rate, and opportunity cost of your down payment.
How much should I put down on a house?
20% eliminates PMI and reduces your monthly payment. But many buyers put down 3–10% and factor PMI into their budget. The affordability calculator shows how your down payment affects your buying power.
What is the 28% rule for buying a house?
Lenders recommend spending no more than 28% of gross monthly income on housing (mortgage principal, interest, taxes, and insurance). At $8,000/month income, that's $2,240 for housing. The affordability calculator applies this rule to find your max home price.
How long does it take to save for a down payment?
At $1,000/month into a high-yield savings account earning 4.5%, a 20% down payment on a $400,000 home takes about 5–6 years. The savings planner shows your specific timeline based on your current savings and contributions.
Should I refinance my mortgage?
Refinancing makes sense when the rate drop is large enough to recoup closing costs before you sell. The refinance calculator finds your exact break-even month so you know whether it's worth it.
Are these calculators free to use?
Yes. NestMath is completely free: no account, no subscription. All calculations run in your browser. Your data stays on your device. The site is funded by voluntary donations through Ko-fi.